1. Field of the Invention
The present invention relates to a foolproof polarity indicator for poled electronics parts or devices to be mounted to a printed circuit board to assure that the poled electronics parts and/or devices are correctly mounted in respect of their polarities to meet occasional requirements dependent on different specifications.
2. Related Art
Almost all electronics parts or devices are mounted on printed circuit boards by using an automatic machine such as a chip mounter, but extra parts or devices or relatively large or odd-shaped parts or devices are handled and mounted onto printed circuit boards by hand. As is well known, some extra parts or devices are required to be oriented and mounted correctly in terms of their polarities.
To assure that such poled parts or devices are always mounted on printed circuit boards correctly in terms of their polarities, it is necessary that polarity indications are given to printed circuit boards. Thus, before permanently fixing poled parts or devices onto printed circuit boards, workers can confirm that the poled parts or devices are correctly oriented on the printed circuit boards. Such polarity indications, however, are too small and hardly visible to the eyes, and therefore, there is still a fear for wrongly mounting such poled parts and devices in respect their polarities. As for the “printed wiring board” proposed in JP 2000-151042(A) prior-mount-visible polarity indication marks are different from post-mount-visible polarity indication marks in size. Specifically, prior-mount-visible marks to help workers correctly orient and fix poled parts or devices are the same in size and shape as poled parts or devices to be mounted (see FIG. 3a).
JP 5-20392(U) discloses a “printed circuit board” on which adhesive labels are attached that describe the specification of the printed circuit board. This facilitates discrimination of similar printed circuit boards in terms of different specifications, permitting common use of the same kinds of printed circuit boards without fear of mounting wrong parts and/or devices.
In the case that similar printed circuit boards are used to provide different products to meet different specifications, it may be required that poled parts or devices be mounted with their polarities actually reversed to what are shown in the indications. In such a case, electrolytic condensers of non-polarity type are used, and printed circuit boards used are also of non-polarity (see FIG. 3b). This remedy, however, has high costs.
As another example of a remedy, two reversed symbol marks are applied symmetrically as shown in FIG. 3(c), indicating that a poled part or device can be reversed in polarity when mounted there. This indication, however, cannot tell which direction is correct with regard to a poled part or device to be mounted there. Also, disadvantageously, extra space available to such dual indication is required around a place at which the poled part or device is mounted. Sometimes, it is required that use is made of an enlarged printed circuit board, which is large enough to provide space available for such dual indications.
One object of the present invention is to provide a printed circuit board bearing foolproof polarity indications to assure that poled parts and/or devices be correctly mounted to meet occasional requests.